Control timing for spatial light modulator

• US 20020130980A1
• Filed: 03/19/2002
• Published: 09/19/2002
• Est. Priority Date: 03/19/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hewlett, Gregory J., Doherty, Donald B.
• Granted Patent: US 6,970,150 B2
• Time in Patent Office: Days
• US Class Current: 348/771
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G09G 3/2037 with specific control of sub-frames corresponding to the least significant bits
• CPC Class Codes: G09G 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: H04N 5/7458 the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]
• CPC Class Codes: H04N 9/3102 using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: H04N 9/312 Driving therefor driving of electronic spatial light modulators in displays other than projection devices G09G3/34, G09G3/36; control of liquid crystal elements G02F1/133; control of micromechanical modulators G02B26/08

Abstract

A spatial light modulator clocking method, called fast-clear, which employs embedded clear hardware in the SLM to enable the fast-clear bit to generate least-significant short-bit periods and without any bit ordering restrictions. In this method, fast data clears 34 are inserted between block data loads 32,36 within a frame refresh period. This method virtually eliminates the artifacts associated with the earlier reset-release timing method without the bit-ordering restriction of the jog-clear method.

Claims

1. A method of operating a spatial light modulator, the method comprising:

loading a first bit of display data into a first block of spatial light modulator elements;

resetting said first block of spatial light modulator elements to display said first bit of display data;

loading a lower-significance bit of display data into said first block of spatial light modulator elements;

resetting said first block of spatial light modulator elements to display said lower-significance bit of display data;

loading clear data in said first block of spatial light modulator elements while simultaneously loading display data into a second block of spatial light modulator elements; and

resetting said first block of spatial light modulator elements to a dark state at the end of a display period corresponding to said lower-significance bit.

2. The method of claim 1 comprising:

delaying the loading of a second associated block of data by an amount corresponding to a minimum number of said spatial light modulator blocks following said step of resetting said spatial light modulator elements to a dark state.

3. The method of claim 1, wherein the display period of said first bit is extended to accommodate said lower-significance bit.

4. The method of claim 1 comprising:

delaying the display of a bit following said bit of less-significance to achieve a minimum off time.

5. The method of claim 4, wherein said minimum off time is further extended to avoid reset conflicts.

6. The method of claim 5, wherein a display period of said bit following said bit of less-significance is shortened by an amount of time corresponding to said further extended time.

7. A projection display comprising:

a light source for producing a beam of light along a first light path;

light-condensing optics in said first light path for focusing said beam of light on to the surface of a spatial light modulator;

control electronics for receiving image data and providing control signals and display data representing said image data;

said spatial light modulator in said first light path for receiving said control signals and said display data and for selectively modulating said beam of light in response to display data, said spatial light modulator comprised of an array of modulator elements, said modulator elements grouped into at least two blocks;

a projection lens focusing said modulated light from said spatial light modulator onto an image plane; and

said control electronics operable to;

load the first bit of display data in a first of said blocks, reset said first of said blocks to display loaded data, load clear data in said first block while simultaneously loading display data into another block, and reset said first block to a dark state; and

sequentially load the first bit of display data into remaining data blocks, resetting each of said remaining blocks to sequentially display loaded data, loading clear data into each of said remaining blocks while simultaneously loading display data into another block, and resetting each of said remaining blocks to a dark state.

8. A micromirror device comprising:

an array of mirror elements logically grouped into blocks;

at least one memory cell associated with each said element;

address circuitry operable to load data into said at least one memory cells associated with each said element of a first block; and

circuitry operable to clear said at least one memory cells associated with each said element in a second block while data is being loaded into said first block.

9. A method of operating a spatial light modulator, the method comprising:

providing a spatial light modulator comprised of an array of display elements logically grouped into at least two blocks;

loading a first bit of display data into a first block of spatial light modulator elements; and

clearing a second block of said spatial light modulator elements during said loading.

10. A method of operating a spatial light modulator, the method comprising:

loading a first bit of display data into a first block of spatial light modulator elements;

resetting said first block of spatial light modulator elements to display said first bit of display data;

loading clear data in said first block of spatial light modulator elements while simultaneously loading display data into a second block of spatial light modulator elements; and

resetting said first block of spatial light modulator elements to a dark state at the end of a display period corresponding to said first bit.

11. The method of claim 10 comprising:

delaying the loading of a second associated block of data by an amount corresponding to a minimum number of said spatial light modulator blocks following said step of resetting said spatial light modulator elements to a dark state.

12. The method of claim 10, wherein the display period of a previous bit is extended to accommodate said first bit.

13. The method of claim 10 comprising

delaying the display of a bit following said first bit to achieve a minimum off time.

14. The method of claim 13, wherein said minimum off time is further extended to avoid reset conflicts.

15. The method of claim 14, wherein a display period of said bit following first bit is shortened by an amount of time corresponding to said further extended time.